If you are still unsure where to submit your piece or would like additional guidance, reach out to the feedback group who is familiar with your pieces.
Chill Subs is a huge, but user-friendly database of literary magazines. You can search by all kinds of criteria including percentage of acceptance rate (or "vibe"), fee or fee free submissions, or whether or not a journal accepts simultaneous submissions.
Submittable is an oldie-but-a-goodie. Like Chill Subs, it is another enormous database of submission opportunites where you can also manage each of your submissions (if a journal uses it to track their subs). The Discover Page is where you can make some headway in finding new opportunities like open contests and calls for submission which the user can then filter by a number of criteria.
Where to submit lists were once limited to the epic (and sadly now defunct) Entropy list. While the writing community is still mourning the loss of the Entropy list--and the amazing journal that created it--there are other communities updating similar content. Heavy Feather Review does a great job here of listing presses looking for full manuscripts, journals and anthologies, as well as fellowships and other opportunities.
New Pages is another database of submission opportunities with handy filters that allow you users search by deadline, genre, and type. Check out this page for any journals or opportunities that may have slipped through the cracks.
What's better than knowing where to submit? Knowing what editors want! Fellow poet Trish Hopkinson has been interviewing magazine editors (and publishing those interviews) for years. In fact, back in my editorial days, she interviewed me. If you are wondering what a particular editor is looking for, check out her where to submit list linked here are well as the editor interviews. She provides all of this free of charge. If you see her in social media land, say thank you!
Brevity is an extremely well-regarded journal that focuses on publishing short works. Their ever-popular Craft Essays section is always worth a read. Lucky for us, they also publish a list of journals and magazines that publish flash nonfiction, which can be a difficult genre to place.